Available light illuminated instrument read-out

ABSTRACT

A read-out for an instrument such as a postal scale which provides either a discrete postal weight range classification or a quantitative weight read-out. The light used for this purpose is merely the available light collected by a plastic prism and internally reflected toward a back-lighted display. In the discrete form of read-out, the display includes a plurality of light pipes, each one of which represents a possible output indicator to be illuminated. Which one is illuminated depends upon the position of a mask which moves in response to the weight indication of the postal scale, and has a transparent window which lines up with the selected one of the light pipes.

United States Patent Conklin [151 3,664,445 1 May 23, 1972 [54]AVAILABLE LIGHT ILLUMINATED INSTRUIVIENT READ-OUT 72 Inventor: Joseph P.Conklin, Fairfield, Conn. [73] Assignee: Pitney-Bowcs, Inc., Stamford,Conn. [22] Filed: May 5, 1969 [21] Appl. No.: 821,835

[52] US. Cl .l ..177/45, 177/50, 177/178,

[51] Int.Cl. ..G01g 23/18,G01g 23/30, G03b 21/00 [58] FieldofSearch..353/40,41,42,3, 1;

[56] References Cited UNITED STATES PATENTS Beck ..-l77/178 Powell177/178 2,471,800 5/1949 Von Mulinen ..353/40 Primary Examiner-LeonardFonnan Assistant Examiner-A. J. Mirabito Attorney-William D. Soltow,Jr., Albert W. Scribner and Martin D. Wittstein [57] ABSTRACT A read-outfor an instrument such as a postal scale which provides either adiscrete postal weight range classification or a quantitative weightread-out. The light used for this purpose is merely the available lightcollected by a plastic prism and internally reflected toward aback-lighted display. In the discrete form of read-out, the displayincludes a plurality of light pipes, each one of which represents apossible output indicator to be illuminated. Which one is illuminateddepends upon the position of a mask which moves in response to theweight indication of the postal scale, and has a transparent windowwhich lines up with the selected one of the light pipes.

1 Claim, 9 Drawing Figures PATENTEUMAY 23 I972 n-1U 1 OF 3 INVENTOR.JOSEPH P, CONKLIN A TTORNE Y P'ATENninmzs 1 12 664,445

sum 3 BF IN VliN'l'Uk. JOSEPH P. CONKLIN ATTORNEY AVAILABLE LIGHTILLUMINATED INSTRUMENT READ-OUT FIELD OF THE INVENTION Theinventionrelates to a read-out for instrumentation of various kinds, andparticularly concerns an available light illuminated read-out for apostal scale.

THE PRIOR ART In recent years considerable attention has been given tothe field of human engineering, in an attempt to design apparatus withinput and output requirements which are better matched to humanoperators. Focusing specifically on the'problem of infonnation output,one of the most successful approaches to the design'of read-outs hasbeen theme of light to back-illuminate an indicator so as to makeitstand out sharply by contrast with the background. This readilyenables the human eye to pickout the illuminated indicator, and providesan efficient man-machine interface.

Illumination is particularly effective in designing read-outs of thedigital or discrete type, as distinguished from the analog or continuoustype in which the indication is in the form of a pointer moving across adial or chart. A good example of a discrete read-out instrument is apostal scale which does not indicate the weight of a piece of main inquantitative terms, but merely indicates the postal weightrangeintowhich the mail falls, so that the user knows how much postage toapply.

In. the past, illuminated read-outs for postal scales and similar small,portable table-top instruments have been troublesome to design. Theygenerally have required some form of internal light source within theinstrument housing, which could be battery-operated or A.C.-operated.The disadvantage of using a battery as a power source is of course thatthe battery has a limited life and needs replacement. In additionbatteries have a tendency to leak and cause corrosion if they are leftin place too long. A.C.-operated light sources also have theirdisadvantages, including shock hazard and the necessity for power cordwhich limits the portability of a small instrument, restricts its use toindoor environments, and presents something of a tripping hazard. Inaddition, A.C. devices generate a good deal of heat and may requirespecial ventilation or cooling. Finally, all light bulbs, regardless ofthe power source, require occasional replacement, which is aninconvenience to the operator and also complicates the design of theinstrument by requiring some sort of access to the interior of thehousing.

THE INVENTION 7 This invention solves the foregoing problems byproviding an available light back-illuminated read-out for a smallinstrument. The instrument has a actuator which moves in response to ameasured condition. The read-out has a transparent display means withfront and rear surfaces, and is arranged to represent differentmeasurements at different locations on the front surface. Availablelight strikes the rear surface and is transmitted to illuminate at leasta part of the front surface, while means interposed in the path of thelight are moveable thereacross in synchronism with the motion of theactuator to divide the front surface into illuminated and shadowedportions, one of which is so positioned relative" to the measurementrepresentations as to indicate the measured condition.

In an instrument which displays a plurality of discrete indications, theread-out comprises a pluralitv of discrete light pipes located in spacedside-by-side relationship, each light pipe corresponding to one of thediscrete instrument output indications. An opaque shutter is formed witha transparent window sized to admit light to one of the pipes at a time,and is moveable in response to the instrument'output to locate thewindow opposite a different one of the light pipes for each outputindication.

No internal light source is required, and the instrument is devoid oflight bulbs, batteries, or A.C. power connections. Thus bulb and batteryreplacement are avoided, there is no need for frequent access to theinterior of the instrument housing, heat'is not generated internally, nospecial ventilation or cooling is required, and the hazards of trippingand electric shock are eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A and 13 are schematicillustrations of a postal range scale employing a discrete read-out inaccordance with this invention, showing the condition of the scale andread-out when the material being weighed is below the lower limit of thepostal range.

FIGS. 2A and 2B are similar schematic illustrations, but show thecondition of the scale and read-out when the material being weighed iswithin the postal range.

FIGS. 3A and 3B. are similar schematic illustrations, but show the scaleand read-out when the object being weighed is above the upper limit ofthe postal range.

FIG. 4 is a perspective view, with parts broken awav for clarity ofillustration, showing the details of construction of the discreteread-out of the preceding figures.

FIG. 5 is a side elevational view, with parts broken away and sectionedfor clarity of illustration, of the same read-out.

And FIG. 6 is a perspective view, with parts broken away for clarity ofillustration, of an alternative type of read-out in accordance with thisinvention.

The same reference characters refer to the same elements throughout theseveral views of the drawing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present read-outoperates to produce a visual output indication, which may be eitherdiscrete or continuous. The application of the read-out to an instrumentwhich measures discrete ranges rather than exact quantities is bestillustrated with reference to a postal weight range scale. Such scalesare ordinarily small, portable table-top devices which indicate onlv thepostage which a letter requires, rather than its weight. Such a deviceshould be free of power cords, and should not have bulkv,heat-generating internal light sources or require replacement of lightbulbs or batteries; yet it can benefit greatly from the advantages of anilluminated read-out.

FIGS. 1 through 5 accordingly illustrate the application of adiscrete'form of illuminated read-out in accordance with this inventionto a postal range scale, specifically one of the kind disclosed inco-pending Pat. application Ser. No. 821,836, filed May 5, 1969 by HenryKorth and Herbert Tramposch, now US. Pat. No. 3,545,556, and entitledWeight Range Scale," which application has a common assignee with thepresent one. Briefly, such a postal range scaleincludes a weighing beam102 which pivots on a fulcrum 104 and has a pin I06 projecting therefromto support an auxiliary weight 108 having an elongated slot 110 toreceive the pin 106. The letter or other object to be weighed exerts aforce on the beam 102 at the left side of the fulcrum 104, as indicatedby arrow 112.

As seen in FIG. 1A, when the weight of the object is less than or equalto one ounce, the combined weight of the object and the auxiliary weight108 is not sufficient to tip the beam 102. But if, as illustrated inFIG. 2A, the object weights more than one ounce, and less than or equalto two ounces, the beam 102 tips and rotates counter-clockwise aboutfulcrum 104 until'the auxiliary weight 108 comes to rest against asupport 114. When the weight 108 strikes the support, it no longercontributes to the tipping force on the beam 102, so that the beam stopsin the position illustrated in FIG. 2A. As seen in FIG. 3A, when theobject to be weighed exceeds two ounces, its weight alone is sufficientto tip the beam 102 to and bevond the point at which the weight 108strikes the support 1 14. As the beam tips further, the pin 106 ridesdownwardly in the elongated vertical slot 1 10.

Thus the postal range scale 100 operates in a digital, or discrete,mode. It has three distinct positions relative to a particular postalweight range: the position of FIG. 1A for mail below the weight range,the position of FIG. 2A for mail within the range, and the position ofFIG. 3A for mail beyond the range.

schematically illustrated in FIGS. 1B, 2B and 3B, and at the right handside of FIGS. 1A, 2A and 3A, is a read-out 118 in accordance with thisinvention which is adapted for use with the postal range scale 100, aswell as with other discrete or digital instruments. The read-outcomprises a housing 120 formed with three display windows 122, 124 and126 respectively. The object of the readout, in terms of the describedoperation of the scale 100, is to illuminate window 126 as seen in FIG.1A when the mail is underweight, to illuminate window 124 as seen inFIG. 2A when the mail is within the weight range, and to illuminatewindow 122 as seen in FIG. 3A when the mail is overweight.

FIGS. 18, 2B and 3B, which show the read-out 118 in the same operatingconditions as FIGS. 1A, 2A and 3A respectively, schematically illustratethe operation of the invention. Within the housing 120 is an opaque maskor shutter 128 secured to the right hand end of the scale beam 102 andmoveable vertically therewith to assume three discrete positions forunderweight, in-range, and overweight conditions respectively. Alignedwith the three display windows 122, 124, and 126 are three light pipes132, 134 and 136 respectively. A transparent window 130 formed in theopaque mask 128 lines up alongside the lowermost pipe 136 as seen inFIG. 1B when the mail is underweight, alongside the middle light pipe134 as seen FIG. 28 when the mail is within the range, and alongside theuppermost light pipe'132 as seen in FIG. 38 when the mail is overweight.A prism 138 is positioned so that an upwardly facing entry surface 140thereof gathers downwardly incident light presented by arrow 142, and areflecting surface 144 thereof internally reflects the light toward allthree light pipes 132, 134, and 136. The mask 128 blocks all of thereflected light except the limited portion thereof which can passthrough the transparent window 130. Thus when the mail is underweightlight emerges only through the light pipe 136 as illustrated by arrow146 in FIG. 1B, and only the lowermost window 126 is illuminated. Whenthe mail is within the range, the light emerges only from light pipe 134as indicated by arrow 138, and only the middle window 124 isilluminated. Finally when the mail is overweight, the light emerges onlythrough light pipe 132 as indicated by arrow 150, and only the uppermostwindow 122 is illuminated.

FIGS. 4 and 5 show the detailed construction of the discrete read-out118. There it is seen that the housing 120 has a generally trapezoidalshape, the slanted front face thereof being formed with a depression 152which defines surrounding ridges 153 above and on either side of thedepression 152. This depression surrounded by the ridges forms a shadedrecess within which to view the illuminated display windows 122, 124 and126, in the manner of a viewing hood. This serves to make maximum use ofthe available light, i.e. the ambient light 142 which is downwardlyincident upon the top face 140 of prism 138.

The far wall 154 of the read-out housing 120 is formed with horizontallyprojecting shelves 156, 158, 160 and 162 which retain and space thelight pipes 132, 134 and 136. The projecting shelves 156, 158, 160 and162 may be integrally molded with the housing 120, using any commonplastic material. In the molding process, suitable apertures are formedin the depressed wall 152 to define the display windows 122, 124 and126. The light pipes 132, 134 and 136 may be formed of any transparentmaterial, such as glass or molded polymethyl methacrylate (Lucite),which has excellent light-conducting properties and is even able todirect light over a curved path bv internal reflection. Making use ofthis property, each of the light pies 132, 134 and 136 is curvedgenerally upwardly as indicated by arrow 148 so that the light whichpasses through any one of the pipes emerges on an upwardly slanted paththrough the associated display window 122, 124 or 126, making thedisplay easier to read when it is on a table top, below eye level/Therearward slant of the housing wall 152 further aids in the reading ofthe display from above. The shelves 156, 158 and 160 are formed withridges 157, 159 and 161 respectively, to accommodate the curvature ofthe light pipes.

The far wall 154 is further formed with an aperture 164 through whichprojects the mask 128 secured to the end of the scale beam 102. The maskmay be formed of any opaque material, and the aperture 130 formedtherein is 'of just the right size to admit light to only one of thelight pipes at a time. The scale beam 102 and mask 128 move upwardly ordownwardly together as indicated by arrows 166 and 168 respectively, toassume three discrete read-out positions, depending upon the weight ofthe mail in relation to the postal range. The size of the aperture 164of course must be large enough to accomodate this vertical movement.

The prism 138 may be made of a material such as glass or Lucite, andrests on a forked supporting bracket 170 which is integrally molded withthe housing and engages the lower comer of the prism so as to restrainit against both horizontal and vertical movement. The upper end of theprism 138 is formed with shoulder 172 around its perimeter to engagewith the margins of a light admitting opening 174 formed in the uppersurface of the housing 120. The light admitting opening 174 allows thedownwardly incident light represented by arrows 142 to enter the prism138, and the engagement between the shoulder 172 and the margins of theopening helps retain the prism 138 in place.

The prism surface 144 is slightly curved to converge the reflected lighttoward the light pipes 132, 134 and 136. In addition it is covered witha coating of silver or other highly reflective material 176 so as toreflect a maximum percentage of the light collected. Of course, all ofthe reflected light (see for example arrows 146 and 150) is blocked bythe mask 128 except for that portion (e. g. arrow 148) which passesthrough the aperture and reaches one of the light pipes (specificallylight pipe 134 in the example illustrated).

This invention is applicable also to a continuous read-out. In FIG. 6there is seen an alternative form of available light illuminatedread-out 618 in accordance with this invention, specifically designedfor use with a continuous type of instrument. A postal scale again isarbitrarily selected for the purpose of illustration, but in FIG. 6 thescale is of the type which provides a continuous quantitative indicationof the actual weight. It has a weighing beam 602 terminating in apointer 628 that moves vertically with the beam (as shown by arrows 666and 668) to a position dependent upon the weight of the mail. Thepointer 628 extends through a suitable opening in a wall 654 of theread-out housing 620. The latter housing has a sloping front wall formedwith a depression 652 and surrounding ridges 653 which define a viewinghood. A display window 622 is formed in the housing wall within thedepression 652, and receives a ground glass screen 623 upon which arerecorded markings comprising a continuous analog weight indicatingchart.

The housing 620 is further formed with an upwardly openinglightadmitting window 674 through which emerges the top face 640 of a glassor Lucite prism 638. Downwardly incident available light represented byarrows 642 enters the window 674 and the prism face 140, and isreflected internally of the prism by a curved surface 644 which isprovided with a silver coating 676.

Exemplary light beams reflected from the surface 644 and coating 676 arerepresented by arrows 648. The locus of all such reflected light beamsforms a tapering wedge of light which converges toward the ground glassscreen 623. The

upper edge of the tapering wedge of light falls at the upper edge of thedisplay window 622, while the lower edge of reflected wedge of lightfalls at the lower edge of the window 622. The reflected light serves toback-illuminate the weight indicating chart on screen 623, and none ofit is blocked by the pointer 628 except for a small horizontal shadowline 635 which reads out the weight in quantitative terms against thechart. The slant of the depressed housing face 652 allows the groundglass screen 623 to face upwardly for easy reading when looking downupon the postal scale at table height.

It will now be appreciate that the read-out of this invention requiresno internal light source, yet provides a bright and readableback-illuminated display which makes maximum use of available light andis particularly designed for easy reading when looking downwardly towardan instrument situated on a table. The lack of an internal light sourceavoids the disadvantages of heat generation, the need for replacement oflight bulbs and batteries, and the weight and danger associated with lvolt powersupplies. The invention is particularly advantageous for usewith the type of read-out in which only one of a plurality of windows isilluminated to give an instantly readable indication of the postal rangeor other discrete fac- 101'.

Since the foregoing description and drawings are merely illustrative,the scope of protection of the invention has been more broadly stated inthe following claims; and these should be liberallv interpreted so as toobtain the benefit of all equivalents to which the invention is fairlyentitled.

The invention claimed is:

1. In a scale having a frame and a beam that is pivotally mounted onsaid frame and is movable between three distinct operative positions,one position indicating that the object being weighed is within apredetermined weight range, while the second and third positions thereofindicate that the object weight is respectively above and below saidweight range;

a display device mounted on said frame and disposed in front of theouter free end of said beam, said display device including threevertically spaced separate window means;

an ambient light gathering and directing prism mounted on said frame anddisposed on the rear side of the outer free end of said beam and inalignment with said window means;

an opaque mask mounted on the free end of said beam and being movablewith said beam to three positions between said prism and display means,said mask having a light transmitting slit formed therein;

the said three operative positions of said beam serving to position saidslit in registry with said three window means respectively so that theambient light gathering, directing and masking action of said prism andmask will produce an illumination in that window means associated withthe weight class of the object that is being weighed.

